Wormholes
If you saw a wormholw in reality, it would appear round, spherical, a bit like a black hole.Light from the other side passes through and gives you a windo to a faraway place. Once crossed, the other side comes for the interview, with your old home visible through the spherical window. But are wormholes real, or are they just magics disguised as physics and maths? For most of human history, we thought space was pretty simple. A big, flat stage where the events of the universe unfold. Even if you take down the set of planets and stars, there's still something left. That empty stage is space, and it exists, unchanging and eternal. Einstein's theory of relativity changed that. Space and time make up that stage together, and they aren't the same everywhere. The things on the stage can effect the stage itself, stretching and warping it. If the old stage was like unmoving hardwood, Einstein's stage is more like a waterbed. It can be bent and even torn and patched, which could make wormholes possible. Our univerese is like a flat plain. Bent in just the right way, wormhole could connect two very, very distant points with a short bridge that can be crossed instantly, enabling you to travel faster than the speed of light. They are theoretically possible and there are different kinds. Einstein-rosen bridges The first kind of wormhole to be theorized was einstein-rosen bridges. They described every black hole as a portal to an infinite pararrel universe. Empty spacetime as flat, but curved by objects on it. If we compress that object, space time becomes more curved around it. Eventaully it beacomes so warped that it collapses into a black hole. Objects become trapped at the singularity at it's core. But maybe there is no singularity. Perphaps this is a wormhole, with another universe like ours on the other end, but mirrored upside down, and time runs backwards. Unfortunetly einstein-rosen bridges cannot be crossed. It takes an infinite amount of time to travel to the other end. If you go in you will not become the stuff coming out, you will only become dead. Very old string theory wormholes If string theory or one of it's variations is the correct description of the universe, then our universe could have a tangled web of thi type of wormhole already. Shortly after the big bang, quntum fluxuations at the smallest scale, far,far smaller than an atom, may have created many string theory wormholes. Between these were tiny strings called cosmic strings. When the universe expanded, the ends were pulled light-years apart. They could be everywhere, waiting to be discovered. There is another way we could get our hands on wormholes: make one. Manmade wormholes The biggest problem we have to solve when making a wormhole is keeping them open, as gravity will try to close them. For very old string theory wormholes, thats the cosmic strings' job. For ours we will need exotic matter. This is not like matter, dark matter or antimatter. It is completley new and different with unprecedented propeties. Exotic matter has negative mass. Objects with postive mass are attractive, they pull objects toward them, and exotic matter would be repulsive. It would push objects away. If we line our wormholes with this stuff, they will balance gravity and keep them open. The Earth could become a wormhole hub, from which we will be able to travel almost everywhere in the galaxy... local cluster? supercluster? Universe? MULTIVERSE?